Geoelectrical and Geoelectromagnetic Imaging in Durusu Basin, Istanbul

Durusu Lake is the biggest and the most important freshwater source which supports drinking water supply to the European side of Istanbul. The formation of the lake is related to the development of a dune barrier that separates the lake from the sea. Because of the importance of lake as a drinking water supply it is urgent to reveal the characteristics of the subsurface system of the narrow coast line between the lake and the sea. In this study (DCR) and (TEM) measurements were applied to detect possible saltwater intrusion and to delineate the subsurface structure in the north of Durusu Lake. When the inversion of these data is interpreted along with the hydrogeology of the area, it is concluded that the salt water intrusion along the barrier is not common and it occurs at a special area where the distance between lake and sea is very close. Along a measurement profile where lake and sea is nearest a water resistivity model was prepared by using borehole data nearby the profile and salt water intrusion was determined.This study revealed the place of clay lenses at the lake system and the influence clay lenses on the water cycle with geoelectrical images.